1. Field of the Invention
The present invention provides for methods and systems for digitally processing a two-channel audio input signal for stereo field enhancement. Specifically, some embodiments relate to digitally processing the two-channel audio input signal in a manner such that immersive studio-quality sound can be reproduced for a listener in a two-channel audio system.
2. Background of the Invention
Stereophonic sound, or stereo, is a method of sound reproduction that creates the perception of directionality of sound. This is achieved by using two or more audio channels played through a configuration of two or more loudspeakers in order to create the impression that sound is coming from various directions. Today stereo sound is common in entertainment systems such as radio, TV, computers, and mobile devices.
In a two-channel audio system, an ideal stereo playback requires the careful placement of two loudspeakers in relations to the listener. The best results are obtained by using two identical speakers, in front of and equidistant from the listener, such that the listener and the two speakers form an equilateral triangle with equal angles of 60 degrees.
However, such a configuration is not always possible or desirable. For instance, many stereo speakers or systems comprise an all-in-one unit, such as a boombox, a sound bar, a cellphone, or speakers embedded into a computer or other device. Further, the configuration of a room may not make it possible for two speakers to be placed equidistantly from the listener. In these less-than-ideal situations, a stereo audio signal cannot be fully appreciated or perceived by the listener.
To compensate for these situations, a “stereo width” control may be implemented for a stereo audio system. A stereo width control allows the image width of a stereo signal to be increased or decreased using Mid/Side (“M/S”) processing. As the width is adjusted, the central sounds remain in the center, and the edges are pulled either inwards or pushed outwards. Specifically, the stereo width of a speaker system can be increased by increasing the level of side signal relative to the middle signal, or decreased by decreasing the level of side signal relative to the middle signal.
However, current static stereo width adjustment methods are not ideal, because different audio signals have different amounts of side signal. As such, it would be beneficial to dynamically control the stereo width adjustment of side signal relative to the middle signal dynamically in order to create a consistent immersive experience in a stereo audio system.